Fluid-activatable device for shut-off under excess flow conditions

ABSTRACT

A fluid-activatable shut-off device, configured as a shut-off valve, has a valve housing formed with a flow passage therethrough and a movably supported valve body, which is movable between an open valve position and a closed valve position. In the open valve position, the valve body is mainly withdrawn from the flow passage, which is thereby essentially cleared. In the closed valve position, the valve body blocks the flow passage. The valve body is arranged to close the valve by abnormal flow conditions by a portion being formed so that the flowing fluid provides a lifting force which affects the valve body and seeks to move it towards the closed position. The valve body may thereby close by an abnormal increase in the fluid flow rate, density or viscosity. The portion may also be supported by an expansion pad arranged to push the lifting surface further into the flow passage as a consequence of changes in the fluid pressure and/or temperature, thereby providing increased lift so that the valve body closes. The valve portion is equipped with plugs for sequentially shutting off the choke channels to the flow of hydraulic/pneumatic fluid between the chambers to thereby control the closing speed of the valve body so that surges is avoided in the pipe system in which the valve is installed.

[0001] The present invention relates to a fluid-activatable shut-offdevice in an embodiment as a shut-off valve or damper for the completeor partial blocking of the flow passage. The shut-off device maygenerally be used in an embodiment as moveable dampers, profiles orsimilar installed in pipes, channels or other flow passages with theobject of arranging a damper/profile in the fluid flow in the desiredposition by using energy present in the flow passage. The invention usedin an embodiment as a valve, comprises a valve housing formed with aflow passage therethrough and a movably supported valve body, movablebetween an open valve position, in which the valve body is mainlywithdrawn from the flow passage, which is thereby essentially cleared,and a closed valve position, in which the valve body blocks the flowpassage and closes the valve.

[0002] The valve according to the invention is generally meant to bemounted into a pipeline, a channel or similar, which carries a fluid(air, water, oil or other liquid- or gaseous media). The valve body isin contact with the flowing fluid and is subjected to compressive andfrictional forces. The valve body is arranged to close the valvewhenever said forces exceed predetermined values. The amount of theforces varies with the fluid pressure, fluid density, flow rate andviscosity.

[0003] The valve is particularly meant to allow shut-off of a liquid orgas flow which intentionally or erroneously is brought to exceed apredetermined upper rate.

[0004] The lifting surface of the valve is generally related to theparameters that are influential, according to the formula:

[0005] Shut-off:

[0006] The formula for lifting force:

L=½·C _(L) ·ρ·A·V ²

[0007] In which:

[0008] L=Lifting force

[0009] C_(L)=Coefficient (empirical, expresses frictional properties ofthe lifting surface versus fluid rheology)

[0010] ρ=Fluid density (influenced by pressure, temperature and fluidcompressibility)

[0011] A=Surface area (effective lifting surface)

[0012] V=Fluid flow rate

[0013] Abnormal flow conditions of a flowing fluid arise in connectionwith, among other things, pipeline breaks which may be caused byaccidents such as explosions, fires and the like, in which abnormal flowconditions of the fluid may contribute to, among other things, greateramounts of undesired liquid/gas being supplied to a possible firecondition.

[0014] Generally, the present invention aims at utilizing a changed flowrate and perhaps also changed viscosity/temperature/pressure by abnormalflow conditions in a flowing fluid.

[0015] According to the invention, it is thereby aimed at eliminatingthe need for external force by utilizing the kinetic (and perhaps thehydraulic, rheologic and thermal) forces which are already present inthe pipeline/channel, the valve body being formed to respond to changesin said forces and close the valve by abnormal flow conditions arising.

[0016] In the immediate following are defined some applications of thefluid-activatable shut-off device according to the invention. Theapplications defined only represent non-limiting examples.

[0017] Accidents at sea-based oil/gas installations have demonstratedhow important it is to have the enormous gas and oil reservoirs presentin the transport line network under control. To a certain degree thecurrent technology manages to control pressure and transport ofinflammable gases or liquids in the pipelines, but situations do occur,in which the valves will be of no use, as breaks in pipelinesimmediately upstream from a valve may release large or small reservoirspresent in the pipeline downstream of the preceding valve. Prior to apossible pipe line break, the valves will be open to allow transport offluid through the pipeline. By closing the valve it will be possible torestrict an oil or gas emission, fire or risk of an emergency situationescalating. This is an operation which will often take a certain amountof time and in some cases such an amount of time that it will be toolate for contributing to significantly limiting the damage.

[0018] In an accident of fire or other emergency situation at sea-basedinstallations it is important to have the liquid flow in the pipesystems carrying explosive/inflammable liquids, under control.

[0019] Today, the liquids in the transport pipe network in the North Seaare mainly controlled by means of so-called subsea valves which arepositioned in central intersections in the pipeline network and/or bymeans of valves placed in the immediate vicinity of the platforms (atarrival or despatch from the platforms). This entails that largereservoirs of gas or liquids may be exposed to explosion, strong heat orother strain which may entail a break in the pipe system aboard theplatform. The only alternative known is then to bleed off pressure, butthis relieving of pressure may take from a few hours up to days. Inprocessing plants situations corresponding to those described abovemight occur by a pipeline breaking at a location in which there is nobarrier against reservoirs of gas or inflammable liquid.

[0020] Subsea valves currently used are based on the use of an actuatorand on the latter being shipped out to the valve. Aboard the platformthe so-called sea-line valves are connected to the operation shut-downsystem of the platform, and are closed automatically on alarm signals.In an emergency situation a subsea valve may, for example, not be closedquickly enough to prevent hydrocarbons from being supplied to theaccident situation aboard the platform, because it takes too long timeto operate the valve. Hydraulics pack and actuator must be shippedacross and connected to the subsea valve for this to close. A sea-linevalve is normally placed somewhat within the platform edge, whichentails that parts of the transport pipeline may be exposed to fire,explosion, falling loads or similar without the possibility of beingable to close the valve by breaks on the seaward side. Large reservoirsof hydrocarbons, oil and/or gas may then be released on the platform andcontribute to the escalation of the accident.

[0021] In the above valve applications a shut-off valve according to theinvention may be used with advantage, because it is arranged to respondto abnormal flow conditions occurring in situations of accidents such asmajor leaks, fire, explosions, in which the valve provides a quick butcontrolled shut-off.

[0022] The constructive features enabling a shut-off valve according tothe invention to respond to an abnormal flow condition of the flowingfluid and thereby effecting forced closing, will be explained after theapplications having been defined.

[0023] Another application in which the method according to theinvention may be used with advantage, is in connection with ventilationof residential houses. Strong wind will cause a draught through openvalves. By mounting the valve according to the invention in valve slotsin windows and/or ordinary rectangular valves, the windward valve willclose while the leeward valve opens and stays open. The dominantpressure inside the house will consequently be a negative pressure. Thiswill have a favourable effect as to the draught conditions in the houseand the drying out of the wall material of the house. According to theinvention, the valve will also have a favourable effect during thedevelopment of a possible fire. The fire will require oxygen in itsinitial phase. The oxygen is brought to the fire through openings suchas doors, windows, valves and other leaks in the house. As the fireinhales, the valve will respond to increased air flow through the valveinto the house by closing. By heat developing, the air expands andcauses a flow of air and flue gases out of the house.

[0024] Another application in which the valve according to the inventionmay be used with advantage, is in connection with explosion dampers. Anexplosion erects pressure waves and will increase the air/gas flowthrough ventilation channels or other openings in the buildingconstruction, also where it is desirable to prevent the fire fromspreading. According to the invention the valve will instantly respondto the pressure wave caused by the explosion, and close, thus preventingundesirable spreading of the fire.

[0025] Another application in which the valve according to the inventioncan be used with advantage, is in connection with ridge roofs on houses.Gale-effected damage, through roofs being blown off the house in a gale,is caused by negative pressure on the leeward side of the roof andpositive pressure building up at the same time on the windward side and,relatively, inside the house. By mounting valves according to theinvention in both roof faces of a ridge roof, the pressure inside thehouse is controlled by the fact that the windward valve closes and theleeward valve opens or remains open. The pressure inside the house willthereby seek to adopt the same level as the pressure on the leeward sideof the roof, and this entails that the lifting effect on the ridge roofdecreases. By mounting valves in all valve slots the same effect will beachieved for the house in general.

[0026] In public waterline network, there are large reservoirs of water,which, on pipelines breaking, may cause great water damages anddestructions. Time for the operation of shut-off valves is critical hereto limit the damages.

[0027] Conventional manually manoeuvrable ball and butterfly valves areused, which depend on personnel being alarmed as soon as possible in anemergency situation. The time aspect in the operation of these knownshut-off valves may thus constitute an essential problem with regard tolimiting damages as a consequence of water leakage.

[0028] Shut-off valves according to the invention may be employed withadvantage in this case. The valve according to the invention is arrangedto enable normal throughput in normal flow conditions for the water inthe pipeline. By a possible break in a water line, subsequent damagewill be limited by the valve according to the invention closingautomatically because of the accelerated flow rate of the waterresulting from the abnormal flow conditions due to the pipeline break.Valves according to the invention could conceivably also be used inbranch lines to a house or at definite places in the house to limitwater damage by a possible pipeline break. The valve may alsoconceivably be used in connection with a garden hose with pertainingvalves and equipment.

[0029] Available energy in a pipe/channel system is the kinetic energyand the potential energy in the form of pressure/pressure differences.

[0030] To close a known shut-off valve which is mounted within apipeline/pipeline system in which a fluid is flowing in abnormal fluidconditions, such as an abnormal fluid flow rate, abnormal pressureand/or temperature, there must be provided in the pipeline/pipelinesystem, upstream from the shut-off valve, a fluid rate indicator, apressure gauge and a thermometer, which are possibly monitoredaudiovisually, followed by manual closing of the valve at criticalparameter values, or the respective meters are connected to an actuatorwhich acts as valve closing device, and which is arranged to close theshut-off valve as a consequence of, for example, an extraordinarydeflection of the pointer of said meter activating the actuator, whichthereby becomes effective and closes the shut-off valve.

[0031] The object of the invention has been to utilize changed fluidflow rate and possibly also changed viscosity/temperature/pressure inabnormal flow conditions of a flowing fluid, directly for the automaticclosing of the valve in a safe and controlled manner and at a very earlymoment in the initial phase of the abnormal flow condition.

[0032] Thus, the invention relates to a fluid-activatable shut-offdevice used in a shut-off valve intended for mounting into apipe/pipeline/channel carrying a fluid. The fluid may be in the form ofliquid or gas. The valve comprises a valve housing formed with flowpassage, which in the mounted state of the valve is brought tocorrespond with the pipe bore or channel of the pipeline etc. The flowpassage may in principle be of any cross-sectional shape (circular,oval, polygonal, square etc.), but it will preferably have the samecross-sectional shape and size as the pipeline/channel to which it isarranged. In a known manner the valve further comprises a movablysupported valve body pivotal between the open valve position, in whichthe valve body is essentially withdrawn from the flow passage therebybeing mainly cleared, and a closed valve position, in which the valvebody directly blocks the flow passage and closes the valve.

[0033] By a fluid-activatable shut-off device of such a kind as definedin the pre-characterizing part of claim 1, the above object has beenrealized through the features appearing from the characterizing part ofclaim 1.

[0034] In order to favour the defined objects, which generally is toenable the automatic closing of the valve as a consequence of anabnormal flow condition of the fluid carried by the pipeline, channel orsimilar, in which the valve is mounted, and whereby said abnormal fluidcondition may be constituted by the fluid flow rate and perhaps alsoviscosity which is an important parameter in the interaction with thefriction between the lifting surface and the fluid and/or pressure andtemperature affecting the density of the fluid, the valve body accordingto the invention is formed and supported so that in the open position ofthe valve, it projects into the flow passage by a relatively smallportion, which is thereby subjected to the flow of a fluid passingthrough the flow passage in a particular direction of flow when thevalve is open. This portion of the valve body, projecting into the flowpassage when the valve is open, is arranged to respond to abnormal flowconditions of the fluid in the flow passage, so as to be influenced byincreased fluid flow rate, changed fluid viscosity and/or temperature,so that the portion and thereby the complete valve body is caused by thefluid to move towards the closed position.

[0035] Said portion projecting into the flow passage of the valve body,the so-called “lifting portion”, preferably has a convexly curved orangled extent at the upstream end. When fluid flows past the liftingsurface of the lifting portion, a lifting movement is initiated, whichseeks to move the valve body towards the closing position. The form,weight and support of the valve body are arranged so that fluid flowingnormally, will not provide sufficient lifting to initiate a closingmovement.

[0036] To make the valve more sensitive to pressure and temperature, anexpansion pad sensitive to pressure and/or temperature may be provided,which, influenced by pressure loss and/or temperature increase, expandsso that the front edge of the lifting surface is moved further into thefluid flow, thereby being more exposed in the fluid flow and increasesthe lifting force across the lifting portion, which results in anearlier time of closing.

[0037] What is required for closing the shut-off valve according to theinvention, is an abnormal flow condition such as explained above. Thelifting portion of the valve body projecting into the flow passage, is,because of its position in the open position of the valve and itsconfiguration (convexly curved and/or angled at the upstreamend—relative to the flow direction of the fluid), respectively, in astand-by position, in which it can very quickly respond to, for example,an increased fluid flow rate caused by a pipe break or other leak.

[0038] The lifting portion of the valve body directed towards the flowpassage may be adapted in terms of friction to the fluid, the influenceof the fluid on said lifting portion and thereby on the valve body,besides the fluid flow rate/properties (viscosity), also being dependingon the surface curvature and surface friction of the lifting portion. Bychanging the flow rate, density or viscosity properties of a liquid, itis possible to control/regulate the closing moment of the valve: Theseare properties of the valve that allow the control of the liquid flow ina pipe system to be based on the utilization of these parameters tooperate the valve. Hover, in most applications of the shut-off valveaccording to the invention its inherent properties are utilized torespond to a particularly abnormal fluid flow rate.

[0039] The valve body is formed as a section of the pipe wall whichforms a tongue-like body placed in a semi-bored cylinder, which cylinderis placed transversely in relation to the flow direction of the fluidflowing therethrough. The valve body is received by a valve housingwhich encloses the lower cylinder half of the valve body. The valvehousing is equipped with a prismatic body having channels or similarthere-through, to bring hydraulic fluid from one chamber to anotherduring the closing process of the valve. This arrangement is provided inthe valve to control the closing movement, so that shock waves areavoided in the pipe system. After an initial swinging up of the valvebody, the closing speed will be determined by how quickly the hydraulicfluid is brought from one chamber to the other.

[0040] Said channels thereby provide for bringing hydraulicfluid/pressure between the two chambers. At the same time the channelwill represent a throttle organ from the flow passage between thechambers, so that a desired restriction of the closing speed of thevalve body is achieved by the fact that the entering of fluid into thechamber is throttled. As the closing function of the valve is inprocess, the pressure difference forces which effect the final part ofthe closing, take over.

[0041] In valves, in which great closing speed does not imply any riskof shock waves in pipe systems causing damages, there will be no needfor the braking mechanism for the closing speed as described above. Insuch cases it will be sufficient with a damper equipped with the liftingportion prescribed.

[0042] The invention is explained in further detail in the following inconnection with a non-limiting example of a presently preferredembodiment, with reference to the drawing, in which:

[0043]FIG. 1 shows a vertical cross-section through a shut-off valveformed in accordance with the present invention, along the line I-I inFIG. 2;

[0044]FIG. 2 shows a vertical cross-section along the line II-II in FIG.1;

[0045]FIG. 3 shows a horizontal cross-section along the line III-III inFIG. 1;

[0046]FIG. 4 shows a vertical cross-section through the shut-off valvein the closed position.

[0047] Reference is made to the figures of the drawing, in whichreference numeral 1 defines the valve housing in general. The valvehousing is formed with a central flow passage 2 there-through, which inthe shown embodiment has a circular cross-section, but which may takeany cross-sectional shape.

[0048] The lower portion of the valve housing is formed as a lying halfcylinder transverse to the direction of flow in the valve. At the bottomof this cylinder seat is provided a prismatic body that defineshydraulic chambers in the open and closed position, respectively, of thevalve. In the prismatic body 8 are bored communication channels 5between the two hydraulic chambers 4 and 6, transporting hydraulic fluidfrom one chamber to the other in the closing and opening processes.

[0049] The valve body 3 has a central portion formed with a bed 9 forthe pivotal support through a cylindrical transverse valve body, and isequipped with a tongue which is formed, in its closed position (FIG. 4),to shut off the passage through the passage 2 completely.

[0050] The valve body 3 projects (relatively insignificantly) into theflow passage by an end portion 7, which has, according to FIG. 1, aconvex curvature upstream (Q defines the flow direction of the fluid).Instead of this convex curvature which, together with the frictionalcoefficient of the end surface 7, is of importance to the function ofthe valve as the closing starts, the end portion—the so-called liftingportion or lifting surface portion respectively—could be formed with oneor more angles.

[0051] In normal flow conditions in the flow passage 2, fluid flows inthe direction Q at a normal flow rate, normal viscosity and normalpressure/temperature. The lifting portion 7 of the valve body 3 issubjected to the flow of fluid, but the lift is too small to move thevalve body towards the closed position.

[0052] Whenever there is an abnormal flow condition resulting in anincreased flow rate, changed viscosity and/or increasing temperatureand/or falling pressure, these changes from normal to abnormalconditions of flow will result in a lifting of the lifting surfaceportion 7 of the valve body. Increased flow rate involves conditions ofnegative pressure in chamber 6 and positive pressure in chamber 4, whichleads to the lifting portion lifting, thereby turning the valve body 3.Changed viscosity directly affects the lifting surface portion 7, whoseradius of curvature and coefficient of friction at the surfacecontribute, likewise, to enhancing the lifting of the lifting portion 7.

[0053] A pressure and/or temperature expansion pad 10 may be positionedimmediately below the tongue portion on the valve body. Pressure loss ortemperature increase in the pipeline will then cause the tongue portionto project further into the flow channel 2 and provide increased lift.

[0054] The valve may also be brought to close by the use of an externalsource for transferring hydraulic fluid from chamber 4 to chamber 6.

[0055] After a preliminary lifting/turning of the valve body, the valvebody 3 will move towards the closed position by means of the increasedlift achieved by the lifting surface 7 to a greater extent being exposedinto the flow passage 2. The closing movement will gradually be takenover by the pressure differential forces across the closing surface.These pressure differential forces also contribute to the valve stayingclosed until pressure equalisation is carried out on both sides of theclosing section.

[0056] The opening of a closed valve is done by first equalizing thepressure on both sides of the valve body 3, whereafter the valve body 3may return to its initial position. The valve body 4 may in a possibleembodiment be configured, sized and arranged to drop back into the openposition through gravity alone, or the valve body 3 may be brought toreturn by the passing of a plug through the valve in the directioncontrary to the normal flow direction.

1. Fluid activatable shut-off device in an embodiment as shut-off valvecomprising a valve housing (1), formed with a flow passage (2)therethrough of desired cross-sectional shape, and a movably supportedvalve body (3) which is moveable between an open valve position, inwhich the valve body (3) is mainly withdrawn from the flow passage (2),which is thereby essentially cleared, and a closed valve position, inwhich the valve body blocks the flow passage (2) and closes the valve,characterized in that the valve body (3) is formed and supported so thatin the open position of the valve, it projects into the flow passage (2)by a relatively small portion (7) which is thereby subjected to the flowof a fluid passing through the flow passage (2) in a defined flowdirection (Q) when the valve is open, which portion (7) of the valvebody (3) by open valve projecting into the flow passage (2), is arrangedto respond to abnormal flow conditions of the fluid in the flow passage(2), so as to be affected by increased fluid flow rate, changed fluidviscosity and/or temperature, so that the portion (7) and thereby thewhole valve body (3) is caused by the fluid to move towards the closedposition.
 2. Fluid-activatable shut-off device according to claim 1,characterized in that the valve body (3) is supported in a valve housing(1) which in its open position forms a first chamber (4) filled with ahydraulic/pneumatic fluid and communicating with a second chamber (6)through choke channels (5), so that in the closing movement of the valvebody (3) the hydraulic/pneumatic fluid is forced from the first chamber(4) into the second chamber (6) through choke channels (5). 3.Fluid-activatable shut-off device according to claim 1, characterized inthat the valve body (3) is equipped with plugs (11) which during theclosing movement sequentially shut off choke channels (5) to the passingof hydraulic/pneumatic fluid between the chambers (4, 6) to lower theclosing speed in the final phase of the closing movement. 4.Fluid-activatable shut-off device according to any one of the precedingclaim, characterized in that a portion (7) of the valve body (3),projecting into the flow passage (2) in the open position of the valve,has a convex curvature at its upstream end relative to the direction offlow (Q) of the fluid.
 5. Fluid-activatable shut-off device according toany one of claims 1-3, characterized in that the portion (7) of thevalve body (3), projecting into the flow passage (2) by open valve, hasan angled portion at its upstream end relative to the direction of flow(Q) of the fluid.
 6. Fluid-activatable shut-off device according to anyone of the preceding claims 2-5, characterized in that a valve bed (9)for slidably receiving the valve body (3), essentially has the form of acylinder section, and that the valve body (3) mainly has a correspondingcircumferential shape.
 7. Fluid-activatable shut-off device according toclaim 6, characterized in that the valve body (3), formed partially as acylinder section, is pivotally supported in the valve housing (1) inwhich there is formed, for this purpose, a central cylindrical bed (9),in which the valve body (3) is slidably supported and which is connectedto the remaining part of the valve body (3).
 8. A fluid-activatableshut-off device according to claim 7, characterized in that saidcylindrical bed (9) forms at least part of that portion (7) of the valvebody (3) which by the open valve projects into the flow passage.